afs: Add file locking tracepoints

Add two tracepoints for monitoring AFS file locking.  Firstly, add one that
follows the operational part:

    echo 1 >/sys/kernel/debug/tracing/events/afs/afs_flock_op/enable

And add a second that more follows the event-driven part:

    echo 1 >/sys/kernel/debug/tracing/events/afs/afs_flock_ev/enable

Individual file_lock structs seen by afs are tagged with debugging IDs that
are displayed in the trace log to make it easier to see what's going on,
especially as setting the first lock always seems to involve copying the
file_lock twice.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index dd28e7679089..744908e0bdec 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1093,6 +1093,7 @@ struct file_lock {
 		struct {
 			struct list_head link;	/* link in AFS vnode's pending_locks list */
 			int state;		/* state of grant or error if -ve */
+			unsigned int	debug_id;
 		} afs;
 	} fl_u;
 } __randomize_layout;